In the construction of roadways and the like, it is common practice to make use of materials such as gravel or small stones as paving materials. These materials can either be used alone or as a base material for other surfaces such as asphalt and concrete. It is further known that quality and durability of the finished paving requires that the base layer be compact to provide a relatively uniform base surface using grading equipment followed by rollers or packers in various configurations.
U.S. Pat. No. 5,395,182 to Rossburger, U.S. Pat. No. 6,119,792 to Almer, U.S. Pat. No. 4,909,663 to Freeman, U.S. Pat. No. 3,993,413 to Cox et al., U.S. Pat. No. 3,291,013 to Stolp and U.S. Pat. No. 3,119,313 to Neidhardt et al. disclose various examples of roller and packer assemblies. In general these assemblies offer minimal relative movement between the wheels or rollers of the assembly to accommodate for obstacles or various ground contours, or alternatively a complex mechanism of bearings and pivoting parts is required in order to achieve a desired degree of relative movement between the rollers.
U.S. Pat. No. 6,520,717 to Otto et al. discloses a walking beam type roller apparatus in which a simplified mechanism of walking beams permits some relative movement between individual pairs of front and rear rollers to accommodate for obstacles or various ground contours in the longitudinal working direction of the apparatus. The walking beams however are pivotally connected along a common fixed pivot axis so that the apparatus is very limited in its ability to accommodate for any differences in ground contours in a lateral direction.
Another walking beam type roller apparatus made available by Handy Hitch Manufacturing Inc. of West St. Paul, Manitoba, Canada involves a plurality of walking beams supported on two laterally oriented support members which are in turn supported on a common frame for towing behind a grader vehicle. On each support member, each walking beam pivot axis is fixed in relation to the pivot axes of the other walking beams which prevents the walking beams from fully accommodating differences in ground contours in the lateral direction.